Many are seeing this as a sign that WB plans to do a movie revolving around Sonya, similar to Capcom's Street Fighter: The Legend of Chun-Li.

However, as Rough Cut Reviews points out:

They could just be going over all of their newly-claimed assets and discovered that none of this sort of paperwork had ever been filed for the Sonya Blade character. After all, isn't it odd how the only paperwork that was filed was for Sonya Blade, and none of the other 50+ Mortal Kombat characters?